1. Field of the Invention
This invention relates to an eye examining apparatus.
2. Related Background Art
(1) In an eye examining apparatus wherein a light beam is projected onto an eye to be examined and the reflected light thereof is received, the alignment of the eye to be examined needs to be performed accurately and therefore, an examiner manually effects the aligning operation. Also, eye examining apparatuses in which delicate alignment is automated are proposed in Japanese Laid-Open Patent Application No. 3-015434 and Japanese Laid-Open Patent Application No. 6-007298.
(2) Further, there are known an eye examining apparatus in which a light beam is projected onto an eye to be examined through a position conjugate with the eye to be examined to thereby effect an eye examination, and an apparatus as disclosed in Japanese Laid-Open Patent Application No. 59-085641 wherein a visual target is presented to both eyes with a variable diopter to thereby effect an eye examination.
(3) In Japanese Laid-Open Patent Application No. 5-000126, there is disclosed an apparatus in which a light dividing member for dividing visible light and infrared light is provided on a visual target unit and a visual target of a wide field of view is presented to thereby effect objective refraction measurement.
(4) In a visual target device, to change diopter without changing the angle of field, there is known a system in which a light beam from a pupil is made into a parallel light beam in front of a visual target and the visual target is moved. Also, as a system in which a portion of an optical system is moved to thereby change diopter, there has been proposed an apparatus in which an afocal converter is moved in the parallel light of a pupil light beam.
(5) Also, there is known a system in which corneal reflected light is received by a light dividing sensor to thereby detect the distance to an eye to be examined.
(6) In Japanese Laid-Open Patent Application No. 5-000126, there are disclosed visual target unit for presenting a visual target to both eyes through a light dividing member and an optical system having a single focus, and a refraction measuring system for effecting refraction measurement through the light dividing member. Also, there is known an eye examining apparatus in which a visual target is presented to one eye and by the changeover of the right and left eyes, an optical system is moved by a predetermined amount in the widthwise direction of the eyes and is three-dimensionally driven for alignment.
(7) Also, there is known a compound machine of an auto-refractometer and an auto-keratometer provided with the refraction measuring system of Japanese Laid-Open Patent Application No. 5-000126, and in addition, a mechanism for moving an optical system including a visual target as a unit for the purpose of alignment.
(i) However, particularly in the apparatus of the example of the prior art described in item (1) above, the examiner manually effects the alignment of the eye to be examined and therefore, accurate alignment cannot be accomplished, and even in an apparatus wherein delicate alignment is automated, there is the problem that at first, the examiner must operate manually.